The present invention relates to an improved roof panel system used on a building to provided increased resistance to wind uplift forces. Particularly, the invention relates to an improved roof panel system which provides increased wind uplift resistance through an improved panel support member which is used to join adjacent panels in a standing seam configuration. The support member of the present invention provides spanning, load-carrying and load-transferring capabilities which are not known in the prior art.
Since about 1990, wind uplift has become an important consideration in the design of roofing systems. In fact, it has been reported that the amount of wind damage to roofs incurred this decade from hurricanes alone amounts to $27 billion. A rectangular roofing surface 100 as is generally known in the prior art is shown in FIG. 1. Such a roofing surface 100 may be broken up into a plurality of areas having distinct wind uplift requirements. A generally square area 102 located in each of the four corners has the highest demand put upon it by wind forces, and this area 102 is referred to as a xe2x80x9cZone 3xe2x80x9d area. Each of the four Zone 3 areas 102 is bounded by two adjacent exterior side edges 104 and two interior side edges 106. The next highest area of wind uplift forces is a generally rectangular area 108 located along the intermediate portions of the roof edges between a pair of the Zone 3 areas. Each of these areas 108, which are also referred to as xe2x80x9cZone 2xe2x80x9d areas, has one exterior side edge 110, a parallel, opposing, interior side edge 112, and a pair of opposed parallel side edges 106. These side edges 106 are, of course, shared with the adjacent Zone 3 area 102. The four Zone 3 areas 102 and the four Zone 2 areas 108 define the outside peripheral area of the roof surface 100 and their direct exposure to the wind forces places the higher demand upon them. The remaining roof surface area 114 is generally designated as xe2x80x9cZone 1xe2x80x9d and it is bounded by two sets of opposed parallel sides 112. These sides 112 are shared by the Zone 1 area 114 and the four adjacent Zone 2 areas 108. It will be customary to lay roofing panels on a roofing surface area 100 in a manner that puts the panels either parallel to or perpendicular to these edges, rather than placing them obliquely.
A typical standing seam roof panel system of the type known in the prior art is taught in U.S. Pat. No. 4,649,684, to Petree, et al., which is commonly owned with the present invention. Petree ""684 teaches a panel system for joining adjacent panels, using a plurality of spaced-apart bent metal clips which are aligned along the standing wall portions of adjacent panels to affix the panels to a building substructure. These clips bear the heavy burden of withstanding the wind uplift forces imposed in service. The surfaces which bear the majority of those forces are a base portion which extends laterally out from one side of the bottom of a connecting wall portion and a plurality of tab portions which project laterally outward from the top of the connecting wall portion. Each of the Petree ""684 clips, as will be explained in more detail below, is affixed to the building substructure only through a single fastener. Unless any adjacent Petree ""684 clips are affixed to the same piece of substructure, they are absolutely unable to transfer any load-bearing capability between them, other than through a roof panel shared by both clips, which is an untenable solution. While the Petree ""684 clips are efficacious, it is necessary to place them on much closer spacings in the Zone 3 and Zone 2 areas than in the Zone 1 area of a roof in order to provide a roof which will resist wind uplift. In some applications, it is simply not possible to place the Petree ""684 clips sufficiently close together to comply with wind-uplift resistance requirements.
It is therefore an advantage of the present invention to provide an improved roofing panel system where clips of the type known in the prior art may be used in some areas, such as Zone 1, but a novel support member possessing capabilities far beyond those of the prior art may be used in association with the roofing panels in Zones 3 and/or 2 to increase the wind uplift resistance.
This advantage of the present invention is provided by a system for roofing a substructure. The system comprises a plurality of roof panels, a plurality of support members and a plurality of cap members. Each of the roof panels comprises a horizontal channel section bounded on opposing edges by a pair of side flanges. An upper end of each side flange is bent to provide a groove which opens outwardly laterally from the panel. Each of the support members has a pair of oppositely extending base flanges and a pair of oppositely extending top flanges. These base flanges and top flanges are positioned along a vertical web member. Each of the top flanges is adapted to be received in the groove of one of a pair of adjacent roof panels. At least one of the two base flanges is adapted to fasten the support member to the substructure. The plurality of cap members have side walls for retaining the top flanges in the grooves. In this way there is no direct fastening of the roof panels to the substructure, so that relative movement is permitted. The top flanges effectively bear the weight of the roof panels. In some embodiments, the support members further comprise a pair of oppositely extending shelf members, one on each side of the vertical web, so that each shelf member is positioned below the channel section of one of the roof panels when the top flange is received in the groove, such that the shelf member bears weight of the roof panel only when the roof panel is deflected, but the shelf member also acts to delimit deflection of the panel side wall.
This advantage of the invention is also achieved through a method for providing a roofing system for a substructure. The method is comprised of several steps. The first step is placing a first roof panel as described above onto the substructure such that one of the side flanges and its groove is exposed. This is followed by the step of placing a first support member as described above adjacent to the first roof panel so the vertical web member is adjacent to the exposed side flange. This allows one of the top flanges to be received in the exposed groove and to bear the weight of the first roof panel onto the top flange. This support member is then fastened to the substructure through an exposed base flange of the pair base flanges which is adapted for fastening, for example, as with having a fastener receiving hole therethrough. A second roof panel, also as described above, is placed adjacent to the first support member so that the groove on the side flange adjacent to the first support member receives the remaining top flange of the first support member to bear the weight of the first roof panel onto the top flange. This leaves the second side flange and its associated groove on the second roof panel exposed. The first support member has now received the bearing weight of two roof panels, and a cap member is placed onto the junction of the top flanges of the support member and the grooves of the two roof panels. The cap member joins the roof panels at the first support member without direct fastening to the substructure by the roof panels. The exposed side wall and groove of the second roof panel are then joined to the roof through a second support member in the manner described above. This process may be repeated a sufficient number of times with additional roof support members, roof panels and cap members to cover the substructure.